The description “a loose sally of the mind; an irregular indigested piece” is attributed to the nature of an essay. This definition highlights the essay’s characteristic as a form of writing that is informal, exploratory, and often unstructured, reflecting the author's thoughts and ideas in a more freeform manner.
Here's how it aligns with each option:
Essay: An essay is indeed often characterized by its exploratory and somewhat informal nature, where the writer expresses their thoughts, ideas, and reflections in a loosely organized manner.
Autobiography: An autobiography is a detailed and structured account of a person’s life. It’s more formal and organized than the description provided.
Epistolary Fiction: This is a genre of writing where the story is conveyed through letters, diary entries, or other forms of correspondence. While it can be informal, it doesn’t specifically align with the description of being a “loose sally of the mind.”
Diary: A diary is a personal record of daily events and thoughts. While it may be informal, it is typically more structured and less “irregular” than an essay.
So, the correct answer being 1. Essay makes sense because it best fits the description of being a "loose sally of the mind" and an "irregular indigested piece."